Revert "Try using an ICE40_CARRY_LUT primitive to avoid ABC issues"

This reverts commit a7632ab3326c5247b8152a53808413b259c13253.

7 files changed, 35 insertions, 102 deletions

diff --git a/techlibs/ice40/arith_map.v b/techlibs/ice40/arith_map.v
index eefc375dd..4449fdc1b 100644
--- a/techlibs/ice40/arith_map.v
+++ b/techlibs/ice40/arith_map.v
@@ -44,32 +44,25 @@ module _80_ice40_alu (A, B, CI, BI, X, Y, CO);
 
 	genvar i;
 	generate for (i = 0; i < Y_WIDTH; i = i + 1) begin:slice
-		ICE40_CARRY_LUT carry_lut (
+		SB_CARRY carry (
+			.I0(AA[i]),
+			.I1(BB[i]),
+			.CI(C[i]),
+			.CO(CO[i])
+		);
+		SB_LUT4 #(
+			//         I0: 1010 1010 1010 1010
+			//         I1: 1100 1100 1100 1100
+			//         I2: 1111 0000 1111 0000
+			//         I3: 1111 1111 0000 0000
+			.LUT_INIT(16'b 0110_1001_1001_0110)
+		) adder (
+			.I0(1'b0),
 			.I1(AA[i]),
 			.I2(BB[i]),
-			.CI(C[i]),
-			.CO(CO[i]),
+			.I3(C[i]),
 			.O(Y[i])
 		);
-//		SB_CARRY carry (
-//			.I0(AA[i]),
-//			.I1(BB[i]),
-//			.CI(C[i]),
-//			.CO(CO[i])
-//		);
-//		SB_LUT4 #(
-//			//         I0: 1010 1010 1010 1010
-//			//         I1: 1100 1100 1100 1100
-//			//         I2: 1111 0000 1111 0000
-//			//         I3: 1111 1111 0000 0000
-//			.LUT_INIT(16'b 0110_1001_1001_0110)
-//		) adder (
-//			.I0(1'b0),
-//			.I1(AA[i]),
-//			.I2(BB[i]),
-//			.I3(C[i]),
-//			.O(Y[i])
-//		);
 	end endgenerate
 
 	assign X = AA ^ BB;
diff --git a/techlibs/ice40/cells.box b/techlibs/ice40/cells.box
index 34d1f372e..d775efa78 100644
--- a/techlibs/ice40/cells.box
+++ b/techlibs/ice40/cells.box
@@ -2,8 +2,12 @@
 
 # NB: Inputs/Outputs must be ordered alphabetically
 
-# Inputs: CI I1 I2
-# Outputs: CO O
-ICE40_CARRY_LUT 1 1 3 2
+# Inputs: CI I0 I1
+# Outputs: CO
+SB_CARRY 1 1 3 1
 126 259 231
-316 400 379
+
+# Inputs: I0 I1 I2 I3
+# Outputs: O
+SB_LUT4 2 1 4 1
+316 379 400 449
diff --git a/techlibs/ice40/cells_box.v b/techlibs/ice40/cells_box.v
index d0eb8708c..e2a54a42c 100644
--- a/techlibs/ice40/cells_box.v
+++ b/techlibs/ice40/cells_box.v
@@ -1,18 +1,12 @@
 (* abc_box_id = 1 *)
-module ICE40_CARRY_LUT (output CO, O, input CI, I1, I2);
-	assign CO = (I1 && I2) || ((I1 || I2) && CI);
-
-	wire I0, I3;
-	assign I0 = 1'b0;
-	assign I3 = CI;
+module SB_CARRY (output CO, input CI, I0, I1);
+	assign CO = (I0 && I1) || ((I0 || I1) && CI);
+endmodule
 
-	//                            I0: 1010 1010 1010 1010
-	//                            I1: 1100 1100 1100 1100
-	//                            I2: 1111 0000 1111 0000
-	//                            I3: 1111 1111 0000 0000
-	localparam [15:0] LUT_INIT = 16'b 0110_1001_1001_0110;
-	wire [7:0] s3 = I3 ? LUT_INIT[15:8] : LUT_INIT[7:0];
-	wire [3:0] s2 = I2 ?       s3[ 7:4] :       s3[3:0];
-	wire [1:0] s1 = I1 ?       s2[ 3:2] :       s2[1:0];
-	assign O = I0 ? s1[1] : s1[0];
+(* abc_box_id = 2 *)
+module SB_LUT4 (output O, input I0, I1, I2, I3);
+	parameter [15:0] LUT_INIT = 0;
+	// Indicate this is a black-box
+	assign O = 1'b0;
 endmodule
+
diff --git a/techlibs/ice40/cells_map.v b/techlibs/ice40/cells_map.v
index d4c611686..d0ddfd02e 100644
--- a/techlibs/ice40/cells_map.v
+++ b/techlibs/ice40/cells_map.v
@@ -57,27 +57,3 @@ module \$lut (A, Y);
   endgenerate
 endmodule
 `endif
-
-`ifndef NO_CARRY
-module ICE40_CARRY_LUT (output CO, O, input CI, I1, I2);
-	SB_CARRY carry (
-		.I0(I1),
-		.I1(I2),
-		.CI(CI),
-		.CO(CO),
-	);
-	SB_LUT4 #(
-		//         I0: 1010 1010 1010 1010
-		//         I1: 1100 1100 1100 1100
-		//         I2: 1111 0000 1111 0000
-		//         I3: 1111 1111 0000 0000
-		.LUT_INIT(16'b 0110_1001_1001_0110)
-	) adder (
-		.I0(1'b0),
-		.I1(I1),
-		.I2(I2),
-		.I3(CI),
-		.O(O)
-	);
-endmodule
-`endif
diff --git a/techlibs/ice40/cells_sim.v b/techlibs/ice40/cells_sim.v
index b5a739a63..322c1e5c7 100644
--- a/techlibs/ice40/cells_sim.v
+++ b/techlibs/ice40/cells_sim.v
@@ -1384,25 +1384,3 @@ module SB_MAC16 (
 	assign LCI = (BOTADDSUB_CARRYSELECT == 0) ? 1'b0 : (BOTADDSUB_CARRYSELECT == 1) ? 1'b1 : (BOTADDSUB_CARRYSELECT == 2) ? ACCUMCI : CI;
 	assign O = {Oh, Ol};
 endmodule
-
-module ICE40_CARRY_LUT (input CI, input I1, input I2, output CO, output O);
-	SB_CARRY carry (
-		.I0(I1),
-		.I1(I2),
-		.CI(CI),
-		.CO(CO),
-	);
-	SB_LUT4 #(
-		//         I0: 1010 1010 1010 1010
-		//         I1: 1100 1100 1100 1100
-		//         I2: 1111 0000 1111 0000
-		//         I3: 1111 1111 0000 0000
-		.LUT_INIT(16'b 0110_1001_1001_0110)
-	) adder (
-		.I0(1'b0),
-		.I1(I1),
-		.I2(I2),
-		.I3(CI),
-		.O(O)
-	);
-endmodule
diff --git a/techlibs/ice40/ice40_opt.cc b/techlibs/ice40/ice40_opt.cc
index edb293b93..f528607d6 100644
--- a/techlibs/ice40/ice40_opt.cc
+++ b/techlibs/ice40/ice40_opt.cc
@@ -47,20 +47,16 @@ static void run_ice40_opts(Module *module)
 			continue;
 		}
 
-		if (cell->type.in("\\SB_CARRY", "\\ICE40_CARRY_LUT"))
+		if (cell->type == "\\SB_CARRY")
 		{
 			SigSpec non_const_inputs, replacement_output;
 			int count_zeros = 0, count_ones = 0;
 
 			SigBit inbit[3] = {
+				get_bit_or_zero(cell->getPort("\\I0")),
 				get_bit_or_zero(cell->getPort("\\I1")),
 				get_bit_or_zero(cell->getPort("\\CI"))
 			};
-			if (cell->type == "\\SB_CARRY")
-				inbit[2] = get_bit_or_zero(cell->getPort("\\I0"));
-			else if (cell->type == "\\ICE40_CARRY_LUT")
-				inbit[2] = get_bit_or_zero(cell->getPort("\\I2"));
-			else log_abort();
 			for (int i = 0; i < 3; i++)
 				if (inbit[i].wire == nullptr) {
 					if (inbit[i] == State::S1)
@@ -83,14 +79,6 @@ static void run_ice40_opts(Module *module)
 				module->design->scratchpad_set_bool("opt.did_something", true);
 				log("Optimized away SB_CARRY cell %s.%s: CO=%s\n",
 						log_id(module), log_id(cell), log_signal(replacement_output));
-
-				if (cell->type == "\\ICE40_CARRY_LUT")
-					module->addLut(NEW_ID,
-						{ RTLIL::S0, cell->getPort("\\I1"), cell->getPort("\\I2"), cell->getPort("\\CI") },
-						cell->getPort("\\O"),
-						RTLIL::Const("0110_1001_1001_0110"),
-						cell->get_src_attribute());
-
 				module->remove(cell);
 			}
 			continue;
diff --git a/techlibs/ice40/synth_ice40.cc b/techlibs/ice40/synth_ice40.cc
index d09a1184c..3faa10b4f 100644
--- a/techlibs/ice40/synth_ice40.cc
+++ b/techlibs/ice40/synth_ice40.cc
@@ -296,7 +296,7 @@ struct SynthIce40Pass : public ScriptPass
 				run("opt_merge");
 				run(stringf("dff2dffe -unmap-mince %d", min_ce_use));
 			}
-			run("techmap -D NO_LUT -D NO_CARRY -map +/ice40/cells_map.v");
+			run("techmap -D NO_LUT -map +/ice40/cells_map.v");
 			run("opt_expr -mux_undef");
 			run("simplemap");
 			run("ice40_ffinit");